Core Summary This U19 proposal aims to achieve islet transplant tolerance in the setting of deceased (Project 1) and living (Project 2) donor transplantation. Both of these projects rely on the use of single cynomolgus monkey donor islets in transplantation tolerance studies. Further, islet processing for studies in Project 2 is especially challenging, as it requires sufficient quantity and quality of islets from partial pancreatectomy to restore glucose control. The main service aim of this centralized Islet Isolation, Quality Control, and Transplantation Core Facility for the U19 is to serve as a reliable resource for high quality monkey islets needed for islet transplantation in Projects 1 and 2, allowing consistent experimental results. We will (Aim 1) support Projects 1 and 2 on this U19 by isolating and distributing islets from deceased and living cynomolgus monkey donors for allo- or auto-transplantation using whole or partial pancreas, respectively; and (Aim 2) provide in vitro and in vivo quality control services on the islets that will be used for transplantation. A total of 12 allogeneic monkey islet transplants are proposed for Project 1 in which islets will be isolated from whole pancreata of donor monkeys after they are euthanized. Islets will be cultured for 24 hours prior to the transplant. A total of 24 partial pancreatectomy and islet isolation procedures will be performed for Project 2 in which islets will be processed from 70% partial pancreatectomy and transplanted back to the donor under kidney capsule immediately after purification. With additional 9 monkey islet isolations needed to test new lots of collagenase and neutral protease, a total of 45 monkey islet isolations for the entire U19 will be performed during the funded period. In order to better interpret the islet transplant outcomes and to be able to compare the results generated from different experimental islet transplantation groups in measuring the success of tolerance induction for islet graft protection, it will be critical to establish an internal control system to ensure all islets used for the transplant studies are viable and functional, as well as comparable between the different experimental groups within each project. We propose to utilize standardized measures, both in vitro and in vivo, to characterize the isolated monkey islets for correlation with allogeneic and autologous transplantation efficacy. These include islet equivalence calculation, sample purity estimation, glucose stimulated insulin release, cell death detection, and a marginal islet-mass transplantation in immunodeficient mice for evaluating islet function in vivo. In summary, the Islet Core will provide the expert technical services for both projects on this application by providing large quantity, high quality, and well-characterized purified monkey islets from individual donors for each transplant. In addition, we will provide consultation to develop strategies for using the services of the Core optimally and for solving problems that may arise. Most importantly, we anticipate the proposed service aims of processing and characterizing monkey islet cells will facilitate the ability of the outstanding investigators on this U19 to conduct research toward a cure for Type 1 diabetes.